1. Field of the invention
The invention relates to a redundant front suspension system for a turboshaft engine mounted on a pylon carried by an aircraft, the word "front" being defined with respect to the direction of flow through the engine to denote that part of the engine which is remote from the flow exhaust zone.
2. Summary of the invention
As is known, an aircraft turboshaft engine is attached to a pylon by means of a front suspension device and a rear suspension device such that the pylon can effect mechanical transmission of the forces between the engine and the aircraft structure. These suspension devices have to withstand the mechanical forces acting along the vertical axis Z due to the weight of the engine, and the dynamic forces acting along the transverse axis Y caused by the movements of the aircraft. The loads produced by the engine thrust and directed along the longitudinal axis X are transmitted to one of the suspension devices by inclined thrust take-up rods disposed on either side of the engine.
Also, for obvious safety reasons the suspension of the turboshaft engine must possess redundancy. For this purpose there are two possible solutions. One is to duplicate all the components of the suspension so that each is adapted to withstand the fixed forces by itself, and the other is to add stand-by components which are arranged to withstand the forces only in the event of a failure of the main suspension.
FR-A-2 680 353 discloses a rear connection structure for attaching a turbojet engine to a pylon wherein a mounting is secured to the pylon and is connected to the engine exhaust casing by three suspension rods, the mounting comprising two parts which are fitted one in the other and which are dimensioned such that each is able to take up all the forces transmitted between the casing and the pylon.
FR-A-2 599 708 also discloses a rear connection device for a turbojet engine, wherein there is provided, in addition to the three known rods, a fourth safety rod which does not take up any loads under normal conditions.
Both of these documents relate only to the rear suspension, and make no reference to means for taking up the considerable X-axis thrust loads in the event of failure of a thrust take-up rod or of the suspension means which normally deals with the load of such rods.